Objects like asteroids and comets in the Solar System can collide with larger planetary bodies, resulting in impact events. When these smaller solar system bodies (SSSBs) strike planets, moons, or other objects, they create a massive explosion similar to a bomb blast. This explosion blows away surface material, leaving behind depressions, nowadays known as impact craters. These craters are usually circular because the explosion causes material to scatter in all directions. Sometimes, oval craters can form if an object strikes at a low angle.
These are the parts of a crater:
Ejecta: When an object impacts the surface, the force of the impact can create a debris field known as ejecta. This is the material that gets blown away from the impact site and can contribute to the overall shape of the crater.
Rim: The raised edge surrounding the depression left by the impact is called the rim. The size and height of the rim depend on the energy of the impact and the properties of the impacting object and the surface it strikes.
Bowl: The central dip of the crater is often referred to as the bowl. It’s the area where the impact energy is concentrated, and it’s usually deeper than the surrounding area.
Central Peak: In larger craters, a central peak can form within the bowl. This peak is a result of the rebounding of the surface material after the impact. It can give complex craters their distinctive appearance.
Terraces or Slumped Walls: In some craters, especially larger ones, terraces or slumped walls can be seen on the interior walls of the bowl. These features are created as the material from the rim collapses back into the crater.
Floor: The bottom of the crater is referred to as the floor. It’s shape and composition depends on the type of impact and the geological characteristics of the region.
Rays: When an impact is powerful, it can create rays of ejected material that radiate outward from the crater. These rays can extend for long distances and can be used to estimate the age of the crater as well.
Secondary Craters: In some cases, the impact of a larger object can create smaller secondary craters around the main crater. These form when ejected material impacts the ground beyond the rim.
There are different types of impact craters:
Simple Craters: These are small, bowl-shaped craters with smooth walls.
Complex Craters: These are larger craters with features like central peaks and stepped sides.
Impact Basins: Impact Basins are extremely large craters over 300 km in diameter. They can create dark areas on the surface of planets or moons.
The size and shape of a crater depend on factors such as the mass, density, and velocity of the impacting object, as well as the geology of the surface it strikes. Larger and faster objects result in larger crater diameters.
